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PVC Machining

05-15-2009, 08:31 AM

Well i finally got set up to finish the bores of my pvc pipe project. 6 inch schedule 40. i machined up a large piece of DOM tube to just fit the od of the pipe. Then wrapped a strip of masking tape (haha hacker LOL) around the outside of the pipe near the end and gently and with a smooth burr free piece of aluminumn tapped the pipe into the holding fixture sort of jamming it into place. it into place. Then i used my homemade 1.5 inch dia bore bar and surprisingly enough wd 40 and the inside bore did not even cloud up after boring. I turned it 100 ropm and .006 per rev. I was surprised something i did worked out. I just sat and watched it bore. Came out nice . Yes i took some pictures and will post some day. later mike

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Mike...Be sure to put a fan behind you, blowing the fumes away from you, while machining PVC. The fumes it gives off contain hydrochloric acid and will make you sick to your stomach (ask me how I know). The fumes will turn steel items around the cutting area a light brown patina. The stuff machines nicely if you radius your tool and will give you a good finish even without a cutting fluid, although WD 40 works well too.

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I hate running PVC* in the lathe. Because the material is basically "pure" there are no "discontinuities" as there would be in a steel alloy from the alloying elements or glass fibers in a material such as Acetal. These discontinuities can aid in the machinability of the material and in getting thechip to break.

Try machining a very pure copper on time. Almost impossible to get the chips to break

* UHMW and nylon are just as bad from a machining standpoint

Forty plus years and I still have ten toes, ten fingers and both eyes. I must be doing something right.

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I think I have seen a specialty material based on acetal with fiberes in it that was advertised as a severe service bearing material. I don't have my Cadillac Plastics book here and can't remember the trade name. Anybody remember something like this?

Jim (KB4IVH)

Only fools abuse their tools.

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Acetal is available glass filled, as is Delrin. Normal generic acetal or Delrin has no filling other than colorant. Acetal and Delrin will chip break if run fast enough with a deep cut but work holding can be a problem under that sort of load.

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As per advice here, I've found when taking long cuts occasionally letting off the wheel or even backing up a fraction of a turn helps prevent those long hazardous strings.

PVC by it's very nature is corrosive of steel. Depending on the additives it can be more or less corrosive. PVC is a science unto itself, and I know only a tiny tiny bit, less than I do about Delrins and Nylons and PE.

Glass fiber... many materials can be ordered with fiber fill... You'll know if you have it. Just be sure to wear a dust mask and clean up really well when done.

As for lube... be careful because certain materials will react to WD-40... either by becoming soft/melting or swelling or discoloring. A quick Google search will tell you if your material will react with the lube/coolant you are using.

Remember! Plastic is not metal, just adjust your speed accordingly and don't try to hog a half-inch at maximum RPM and you'll be fine.

This product has been determined by the state of California to cause permanent irreversible death. This statement may or may not be recognized as valid by all states.Heirs of an old war/that's what we've become Inheriting troubles I'm mentally numbPlastic Operators Dot Com

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For posting some of my Homemade Tube Machining Gizmoes. It came out very nice, I machined the Pipe top a very close to O D of PVC Diameter (.002) and the aluminiumn round thing is used to press slide the pvc Tube out of the DOM holding Fixture after machining. Thanx again Evan for the Help with pictures.